The present invention relates to a method and a device for controlling processes in conjunction with a drive, in particular an engine in a motor vehicle, the processes being executed and controlled at the time the drive is shut off and/or thereafter. German Published Patent Application No. 33 27 376 describes a method and a device for controlling the position of the throttle valve in the intake pipe of an internal combustion engine. When the throttle valve is shut off, it is initially moved to the closed position for a predefined period of time and thereafter it is opened again. Current supply for an appropriate electronic control unit is maintained for this purpose by a timing element after the internal combustion engine is shut off. Thus the internal combustion engine is safely shut off without subsequent uncontrolled combustion, and subsequent reopening prevents the throttle valve being cooled from seizing. The first control unit, which controls the defined timing of valve opening and closing, is disconnected from the power supply by a timing element during after-run.
When multiple processors or controllers are used, the use of a timer element represents a problem due to the lack of coordination of the processors, because problems may occur due to a sudden loss of power supply triggered by a timer element when critical processes are run by a plurality of uncoordinated processors. Thus the related art cannot provide a method that is optimum in all respects.
Therefore, an object of the present invention is to have each processor or each controller perform their functions independently in the after-run phase and yet carry out after-run termination, i.e., the disconnection of the control units from the power supply, in a coordinated manner.
The present invention is based on a method and a device for controlling processes with the help of process quantities in conjunction with a drive, in particular an engine in a motor vehicle, the processes being executed and controlled at the time the drive is shut off and/or thereafter, and power supply being maintained by at least one energy storage device at the time the drive is shut off and/or thereafter. The processes are controlled by at least two processors or controllers, the first processor disconnecting the at least second processor from the power supply or shutting it down when the process quantities meet a predefinable condition. The process quantities and/or the at least one predefinable condition are transmitted by the second processor to the first processor. Subsequently the first processor evaluates the transmitted information of the second processor and its own process quantities and the conditions they are to meet and disconnects itself, as well as the controlled system from the power supply by the at least one energy storage device.
The end of the process runs or their control is advantageously represented by the process quantities or the predefinable conditions, so that when the system is shut off it can be ensured that all processes, including the safety-critical processes, are brought to an end in a controlled manner before the power supply is disconnected.
By using several processors and coordinating after-run shutoff through them, various functions can be run by the individual processors even during after-run. Thus advantageously a separation of functions in the controller and safe shutoff are possible.
If no time condition is used as a condition, it is conveniently not necessary that the processing times of the individual after-run functions be known, for example, in order to set a timer element accordingly. Thus, even unforeseen events, which extend the time of the after-run function runs, for example, do not impede a coordinated, controlled, and safe shutoff.
Due to the coordinated shutoff only when the controlled processes have reached a safe status, it is advantageously not necessary that the after-run functions be symmetrically distributed among the processors or even the tolerances of components or applicable data in designing the system be taken into consideration.
Thus, after-run time is always the shortest possible under the different operating conditions, i.e., power supply is always shut off as soon as possible. Excess power consumption and therefore unintended depletion of the at least one energy storage device in the vehicle, in particular the vehicle battery, is thus advantageously avoided. If after-run shutoff is expediently carried out by one of the processors, a common after-run power supply can be used for all processors or the complete digital portion and/or additional circuit components, in particular the controlled system, resulting in advantages concerning the complexity and cost of the hardware circuitry.
Since the interfaces between the processors are present anyway, typically for information exchange, also the information allowing coordination of the after-run shutoff can be transmitted through these interfaces, so that no additional hardware is necessary.
An additional advantage is that the at least two processors can be arranged in any desired manner, i.e., they can also be advantageously distributed over multiple controllers. Thus coordination of the after-run shutoff advantageously takes place so that information between the controllers is reliably exchanged.